Outboard motor assembly



May 24, 1938.- o. c. LlNTHwArrE 2,118,209

OUTBOARD MOTOR ASSEMBLY Filed Jan. 1e, 1955 2 sheets-sheet 1 l INVENTOR. OWEN ACI UHTHwa/TP mi ffl/QW ATTORNEYv May 24, 1938- o. c. LINTHWAITE 2,118,209

QUTBOARD MOTOR ASSEMBLY Filed Jan. 16, 1935 2 She =zr,s-Sheo%l 2 IN VEN TOR.

ATTORNEY UNITED .STATI-:s fPArENr oF'FlcE about an axis` adjacent to, but

lations of the boat.

Patented May 24, lassv vOU'IBOARD MOTOR ASSEMBLY Owen C. Linthwaite, South Bend, Ind., assigner to Bendix Products Corporation, Ind., a corporation of Indiana South Bend,

Application sammy 1s, 1935, sex-iai No. 2,085 2 (c1. 11s- 18) This invention relatesto power plants, and more particularly to the internal combustion engine type of power plant adapted particularly for use with water-craft. The particular type of engine referred to herein is commonly known as the Aoutboard motor,' and is characterizedV by the fact that the motor is turnable about. an axis to eifect the steering of the craft to which the motor is attached.

One feature of the invention relates to novel means for attaching themotor to the boat in such a manner that adjustments of the angle between the drive shaft of the motor and the transom of the boat may be easily and quickly made without interrupting the operation of the motor or moving it from the transom of the boat. Preferably the motor is provided with adjustable means for attaching it to any boat regardless of the angle of the transom.

Another feature has to do with novel steering means so arranged that the motor isturnable not concentric with, the propeller shaft to effect'steering oper- I prefer to provide the motor with a novel co-pilot having a manually operable member to fix the engine against steering movements or to cause it to steer a predetermined course.

Other features relate to novel means for preventing engine vibration from being transmitted to the boat; to an improved Venturi exhaust effect wherein the exhaust gases are discharged from the engine at the most restricted section of the passage and are immediately directedinto a flared passageA to-reduce back pressure of the gases; to a novel stream-lined drive shaft housing an'd exhaust passage wherein a portion of the housing is employed as an expansion chamber for exhaust gases; to the provision of a streamlined under-water exhaust passage communicating with the interior of the drive shaft housing, and adapted todischarge exhaust gases beneath the surface of the water but above the anti-cavitation plate; to an improved combination of a bladed. flywheel with a stream-linedhood provided with Ventilating louvres for air-cooling the motor; to a novel resilient tiller for steering the craft; and to the arrangement of a stream-lined rubber mounted fuel tank supply fuel' to the engine.

Another object of theinvention' is to prevent water from entering the lowerv propeller gear housing.- w

Having the above and other objects particularly inv mind the invention comprehends the.

combination and arrangement of parts hereinafter fully described andillustrated in the accompaying drawings, submittedfr purposes of illustration only, and notintended to-deflne cooled cylinder and the cooling ns beneath the engine to is .provided with a flanged hub rality ofnotches 38 positioned lthe scope of the invention,"-reference being had for that purpose to the subioined claims.

In the drawings, wherein similar reference characters refer to similar parts throughout the several views: l

Figure 1 is a side elevation, partly in section.

of an outboard motor embodying the presentinvention;

Figure 2 is a side elevation, partly in section,

on a larger` scale, showing the means by which,

the motor is attached to the boat;

Figure 3 is a view on the line 3-3 of Figure 2;

Figure 4 is a sectional view on the line 4--4 of Figure 1; and

Figure 5 is a perspective view on the line 5 5 of Figure 1.

Referring to the drawings and more particularly to Figure 1, there is shown a portion of a boat having a transom l0 adapted to receive an outboard motor assembly indicated as a whole by the reference numeral I2.

`'I'he outboard motor assembly I2 inc ludes'an internal combustion I4, and, in the preferred embodiment, an air- I6, and a flywheel I8. 'I'he ilywheel I8 is provided with a plurality of fan blades 20 to force air to flow over the crankcase I4,

22 of the cylinder I6 to prevent those parts from becoming too hot due to the heat of combustion.

The engine is surrounded by a stream-lined hood having a lower section 24 and an upper. section 26. The stream-lined hood infparts a graceful appearance to the engine and materially assists in directing the flow of cooling air overthe engine parts and out through the cooling louvres 28. If desired, the fan blades 20 flywheel I8 may be positioned to draw air in through thelouvres 28 and force it downwardly over the engine parts and discharge it below the lower section 24 of the hood.

A stream-lined fuel tank 30 positioned beneath thelower section 24 of the hood is carried'on rubber mountings 32 andV supplies liquid fuel for 4the operation of the engine.

A lever 3,4 projecting through the lower section 24 of the v hood actuates alatch to release the upper section 26 of the hood andsets the spark, throttle and choke valves of the carburetor in the starting positions. The flywheel I8 36 having a plutherein to receive one end of a knotted rope wrapped around the hub 36 to rotate the engine for starting purposes.

The power of the engine is transmitted to a propeller 40 through a drive shaft 42. The drive shaft 42 passes through an upper stream-lined housing 44 and a lower stream-lined housing 46. Thezfupper and lower housings are jointed toengine having a crankcasel carried by the' closely adjacent to gether by any suitable means such as the bolts 48.

The lower housing 46 is provided at its lowermost extremity with a propeller protecting fin 56, which travels ahead of the propeller 46 to engage any obstacle which might injure/,the propeller and move the propeller to 'ya position to avert damage thereto by a mechanism to be hereinafter more fully described.

Immediately above the fin 56 is a propeller drive gear housing 52. 'I'he drive shaft 42 is'fltted with a ,bevel gear which carries the propeller 46. The lower housing is provided with an anticavitation plate 66. The plate 66 has a smooth dat lower surface and lies a short distance above the propeller. The housing 46 is stream-lined below the plate 66 to prevent air from pocketing in front of the propeller 46 due to the forward movement of the boat through the Water. The proportions and size of the plate 66 vary in accordance with the speed at which the boat is propelled through the water, that is a motor designed for racing or high speed operation will be designed with a smaller anti-cavitation plate than one intended for slow speed or pleasure operation.

'I'he upper housing 44 is divided into two chambers 62 and 64 by a partition wall 66. The drive shaft 42 passes through the chamber 64, and into a chamber 66 formedlin the lower housingv 46. A casing vmember 16 surrounds the shaft 42 and protects it from water, gases, etc. The casing 16 is pressed into fluid-tight relationl with the upper portion of the propeller drive gear housing 52 at the lower end, and is a pressed t through an aperture in the upper end of the'housing 46. Water is prevented from entering thevhousing 52'from the propeller side by the novel packing illustrated in Figure 4. The propeller shaft 68 is provided with a section of reduced outer diameter 12. The shaft 58 rotates in a bearing 14, pressed into a plate 16. 'I'he plate 18 is fastened to the housing 52 in any suitable manner as by the studs 18. The end of the bearing 14 is concave as at 86 to coincide with the end of the section of larger outer diameter of the shaft 58. The plate 16 is provided with an extension 82 having a contracted outer portion 84 adapted to lie the section of reduced outer diameter of the shaft 58. The space between the sections 12 and 86, and the contracted outer portion 84 of the extension 82 is packed with cork or' other suitable packing material 86. In order for water to pass along the shaft 58 to the housing 52 it must follow a tortuous course, and water v is thus effectively prevented from entering the housing, and the gear lubricant is successfully retained therein. A,

The exhaust gases pass from the engine through a short casingv member 88 interposedl between the exhaust outlet of the engine and the chamber 62 in' the upper housing 44.- 'I'he chamber 62 communicates with the chamber 68 in the lower housing 46. 'l

The housing 46 isprovided with a stream-lined fin 86 positioned 66 to assist in steering the boat, and to reduce the turbulence of the water flowingpast the housing 46. The lower portion o f the fln is expanded laterally as at 92 to form -a stream-'lined vexhaust outlet 94 communicating with the chamber 68 in the lower housing 45- f .v

Itwill be observed that a Venturi exhaust ef- 54 which meshes with another bevel gear 56 fixed to a propeller shaft 5 above the anti-cavitation platev fect is obtained by 4discharging; the exhaust gases from the engine at the most restricted crosssectional area of the casing member 88. The. exhaust gases travel gressivelyv increasing cross-sectional area of the casing member 88 and the chamber 62 formed in the housing 44 and discharge into the chamber 68 formed in the housing 46.

The increasing area of the exhaustpassages 88V and 62 permits the exhaust gases to expand gradually. 'I'he chamber 68 forms a convenient and suitable expansion chamber which, together with the progressively increasing volume of the chambers above prevent back pressure from being exerted upon the engine.

Water flowing over the finof the housing 46 cools the exhaust gases in the chamber 68 thereby causing them to contract and drop to the lower portion of the chamber 68 where they are discharged through the exhaust outlet 64Min the fin 96. lI'he exhaust gases are thus discharged beneath the surface of the water but above the anti-cavitation plate 66. The result is that quietv operation of the engine is effected, andthe exhaust gases are discharged to the rear of the propeller so that the density of the water iiowing past the propeller is not decreased.

'Ihe operation of the device thus far described is as follows. To start the engine the operator moves the lever 34 to unlatch the upper section 26o! the hood; retard the spark, and set the choke and throttle valves of the carburetor to the starting position. A knotted rope, one end of which engages one of the notches 38, is then wrapped around the flanged hub 36 and the engine rotated by pulling the rope, in the known manner.

When the engine starts to operate on its own power the upper section 26 of the hood is closed. Air is drawn by the rotating blades 20 of the flywheel I8, through the lower section 24 of the hood, over the engine parts, to absorb heat therefrom, and is then driven out through the louvres 28 formed in the upper section 26 of the hood.

Power is transmitted from the engine bythe downwardly through the pro- A of the housing 44, and the casing 16 in the chamber 68 of the lower housing 46, to the propeller drive gear housing 52. In the housing 52 a bevel gear 54 carried by the drive shaft 42 meshes with another bevel gear 56 fixed to the propeller shaft 58 to drive the propeller 46 carried by the shaft 58. Water is prevented from entering, and the gear lubricant is prevented from escaping from the housing 52 by the novel packing means fully described heretofore.

The exhaust gases pass from the engine exhaust passage into the casing member 88 wherein a limited amount of expansion is permitted. The gases then pass to the chamber 62 wherein further expansion occurs, and the gases are forced downwardly into the chamber 68 where considerable expansion of the gases is permitted. The temperature of the gases is rapidly lowered due to the cooling effect of the water flowing over the lower portion of thehousing 46 and the fin 86. 'I'he volume of gases is thereby rapidly decreased and they move toward the bottom of the chamber 68, and are discharged through the exhaust outlet 84 below the surface of the water.

Novel means are provided to fix the motor to the transom i8 of the boat to be propelled. The motor is suspended on a U-shaped pressure plate |86, having a reinforced portion |62, and rigidifying flanges |84. The upper end of the pressure erally extending projections |20 Aand through resilient bushings ||0, which may be made of rubber or other suitable material, received within a housing 2 carried by the upper housing member 44, and is held in place by a nut I4.

The bearing surface |06 carried by the upper end of the pressure plate is engaged by an adjustable 'clamping bracket ||6 having a manually operable thumb screw I8 to vary the resistance to turning movement between the motor and the pressure plate |00. 'Ihis feature is commonly referred to as the co-pilot and will be more fully discussed'hereinafter.

The clamping bracket I6 is provided with lat- |22. These projections are adapted to receive bolts |24 to nx the clamping bracket ||6 to the housing member 44g Resilient bushings |26, made of rubber or other suitable material, are positioned between the bolts |24 land the housing 44 to damp out vibration, and to coact with the bushings ||0 to electrically insulate the motor from the boat.

'I'he projection |22 of the clamping bracket I6 is provided with a tiller |28 for turning the motor about the axis of the pressure plate |00 for steering the boat.

'I'he resilient bushings |26 permit the'motor to vibrate freely about the axis of the plate 00 an amount equal to the natural amplitude of its torque vibration. A minimum force is therefore required on the tiller |28 to hold the motor in any desired position or tion for steering the boat.

'Ihe operating end of the'tiller is flexible, haV- ing a coiled spring or other flexible member |30 embedded in a resilient handle 32 formed of rubber or other suitable material. Vibration of the motor is thus damped out, and the grip |32 is electrically insulated from the motor.

The pressure plate 00 carries a pair of supporting braces |34. A pressure arm |36 is pivotally mounted on a bolt |38 passing through the supporting braces |34. One end of the pressure arm |36 abuts the reinforced portion |02 of the pressure plate |00. The other end of the pressure arm |36 is provided with screw threads |40 to receive one end of a pressure screw |42. The other end of the-screw |42 is held by a pressure bar |44.. The pressure bari 44 extends between and is xed to a pair of U-shaped attaching brackets |46. The brackets |46 are pivoted on the bolt |38, carried by the supporting braces |34, and are provided with boat |48 which coact with thumb screws |50 threaded through the other leg of the bracket |46 to hold the motor i-n place on the transom l0 of the boat.

Means are thusprovided for varying the angle between the drive shaft-42 of the motor and the transom I0 of the boat. 'The motor is thus capable of being used on any boat regardless of the angle of transom.

To attach the motor to any boat the brackets |46 are placed over the transom with the boat engaging surfaces |48 contacting the outboard side of the transom. then'tightened to fix the bracket |46 in place. The pressure screw |42 is then rotated to move the motor to any desired angle with respect to to move it topany new posiengaging surfaces The thumb screws |50 are the transom i0. By rotating the screw |42 to project it further through the pressure arm |36 will move the lower portion of the drive shaft 42 in the clockwise direction as viewed in Figures 1 and 2, thereby increasing the angle betweenthe drive shaft 42 and the transom |0. Y

In operation thevthrust of the propeller 40 is exerted upon the pressure arm |36, transferred through the pressure screw |42 to the pressure bar |44 positioned between the attaching brackets |46and then exerted upon the transom I0, to move the boat through the water..

Thev reinforced portion |02 of the pressure plate |00 is held in contact with the end of the pressure arm |36 by the weight of the engine and the thrust of the propeller. The motor is however free to swingabout the bolt |38 'so that if the lower housing 46 or the iin 50 strikes against an object the motor will swing up pivoting about the bolt 38 to avoid injuring the propeller 40.

To steer the boat, the operator grasps the resilient handle |32 and rotates the tiller |28 fixed to the motor. 'Ihe motor rotates about the axis of the pressure plate |00 to effect the steering of the boat.

If desired, the thumb screw 8 can be rotated to tighten the bracket ||6 on the bearing surface |06 to hold the motor from rotation about the axis of the Apressure plate |00 While starting the engine or to cause the boat to which the motor is attached to steer any desired predetermingd course. The operator is thus relieved of a portion of the physical laborrequired to steer the boat.

The housings 44 and 46 together with the means for attaching the motor to the boat are so designed that other forms of power plants may f be substituted for the power plant shown and described herewith where greater power is required.

For instance, a power plant having opposed or parallel cylinders may be employed, and the cooling of this unit may be by air or by liquid.

While the invention has been described with particular reference to a preferred embodiment,

lit is not intended to limit the scope of the invention to the embodiment shown, nor otherwise, than by the terms of the following claims.

I claim: n

l. In an outboard motor, an engine, a propeller, a drive shaft housing comprising upper and lower sections interconnecting the engine and propeller, an exhaust outlet from the engine, means including diverging walls forming a downwardly extending passageway in the upper section, and means including a rearwardly directed under-water exhaust outlet in the lower section of the hqusingto permit the escape of the expanded gases without heating the engine.- l 2. In an outboard motor, an engine,L a propeller, a drive shaft `housing comprising upper and -lower sections interconnecting the engine and propeller, a drive shaft in said housing, an exhaust outlet from the engine, means including diverging walls forming a downwardly extending passageway in the upper section of said housing, means including a rearwardly directed under-water exhaust outlet in the lower. section of the housing to permit the escape of the expanded exhaust gases without heating the engine, and a liner surrounding the drive shaft.:

OWEN C. 

